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The number of obese individuals has increased dramatically—now, approximately 30 percent of Americans are obese, according to the Centers for Disease Control and Prevention, up from about 15 percent in 1980. Cancer rates are increasing in parallel with obesity, and recent evidence suggests that obesity may be responsible for about half of all cancers in the U.S.

Parekh’s study aims to better understand this linkage, which may center on the body’s insulin.

“It has been theorized that insulin acts as a growth factor for cancer cells and produces an overall environment that is conducive to cancer development,” explained Parekh, a faculty member in NYU Steinhardt’s Department of Nutrition, Food Studies, and Public Health. “Obese persons commonly have higher blood levels of insulin, which may enhance their risk of cancer.”

But the genes under the influence of insulin involved in the onset of cancer have not yet been studied, Parekh noted.

“Furthermore, diets high in refined carbohydrates including sugars, refined flour and grains, may increase insulin levels in the blood and thereby contribute to cancer development,” she added. “The mechanisms through which, carbohydrate nutrition and our genetic material work together in the development of cancer are currently not well understood and have not been adequately studied in humans.

“Taken together, there are several unanswered questions surrounding the insulin, carbohydrate diet, and cancer connection. Understanding this connection is a critical control point for the prevention of cancers in which obesity may be a primary cause.”

Her study, the Cancer, Insulin Resistance, and Lifestyle (CIRCLE), aims to address these knowledge gaps by investigating the separate and combined impact of blood markers, genetic factors, and diet related to insulin and glucose metabolism in the development of obesity-related cancers.

The project will use data from the Framingham Heart Study. In this study, which began in 1948 and continued through 2008, researchers gathered demographic, diet, medical history, and physical history through in-person interviews and questionnaires at different periods—some for up to 60 years after the initial interview. The main objective of the study was to determine the factors that produce cardiovascular disease, but the researchers also tracked diagnoses of cancer.

“This research will provide important information about missing links required to target prevention of obesity-related cancers,” said Parekh. “Its ultimate purpose is to identify individuals with high insulin or blood sugar levels, so we can recommend healthier diets or genetic screening as tools to head off cancer in a substantial at-risk population.”

Niyati Parekh, an assistant professor at New York University’s Steinhardt School of Culture, Education, and Human Development, has received a $720,000 Research Scholar Grant from the American Cancer Society to study the role of insulin in obesity-related cancers.